Experimental Study of a Flameless Gas Turbine Combustor

Abstract

This paper presents experimental data, performed at atmospheric conditions, on a novel flameless combustor with application to gas turbine engines. Flameless combustion is characterized by distributed flame and even temperature distribution achieved at conditions of high preheat air temperature and sufficiently large amounts of recirculating low oxygen concentration exhaust gases. Extremely low emissions of NOx, CO, and UHC are reported in this paper for flameless combustion in a multiple jets premixed gas turbine combustor. Measurements of the flame chemiluminescence, CO and NOx emissions, acoustic pressure, temperature field, and velocity field reveal the influence of various parameters including: preheat temperature, inlet air mass flow rate, combustor exhaust nozzle contraction ratio, and combustor chamber diameter on emissions and combustion dynamics. The data indicate that greater air mass flow rates, thus larger pressure drop, promotes the formation of flameless combustion and lower NOx emissions for the same flame temperature. This flameless combustor is basically a premixed combustion in which NOx emissions is an exponential function of the flame temperature regardless of different air preheating temperatures. High preheat temperature and flow rates also help in forming stable combustion which is another advantageous feature of flameless combustion. The effects of the combustor exhaust contraction and the combustion chamber diameter on emissions and combustion dynamics are discussed.